1.4 Sea-Floor Spreading



Vocabulary


sea-floor spreading-the process of continually adding new material to the ocean floor. (see diagram)
deep-ocean trenches- a deep underwater canyon where the sea-floor goes back into the mantle.
subduction- the process of when the ocean floor sinks back into the mantle.
sonar- a device that bounces sound waves off underwater objects
Mid-ocean ridge- the longest chain of underwater mountains


Outline


Mapping the mid-ocean ridge

  • Evidence from sea floor spreading
    • evidence from molten material
    • evidence from magnetic stripes
    • evidence from drilling samples
      • older rock pushed to sides

Subduction and Earth's ocean


subduction in the Pacific ocean

    • subduction in the Atlantic ocean